1. Field of the Invention
The present invention relates to a thermal printer adapted for printing characters and bar codes on paper sheets, such as labels.
2. Description of the Related Art
As an example of the conventional thermal transfer printer of this type, there is a label printer which is disclosed in Japanese Patent Disclosure No. 61-266271 (corresponding to U.S. Pat. No. 4,744,680, issured on May 17, 1988) by the same applicant.
In this label printer, characters and bar codes are printed on a label sheet by means of a line thermal printing head with a large printing width. In printing, the printing head is pressed against a platen with a ink ribbon and the label sheet between the head and the platen. This precedent invention is characterized in that a printer unit, in which a line thermal head and ink ribbon supply and take-up spindles are mounted on a pair of frames, is rockably or movably attached to a fixed mechanism section of a casing of the printer.
According to the prior art printer described above, it is very difficult to set the paper sheet in a predetermined printing region as performing a positioning operation, so that defective printing or waste of printing paper may be caused.